I got this error while looking at a customer’s system, and weirdly, all renderings that used datasources had stopped working.

Sadly, I don’t still have the full stack trace, but it turns out the problem was a mis-configured URL for the SOLR service. Sitecore uses content search to find the datasource for a component.

This fact was a new one for me!

I think our URL lacked a /, or /#/. We corrected it, and the error went away – and our datasourced renderings started working again.

I found a reference on StackExchange after the fact.